US6251545B1 - Method and system for improving transmission of light through photomasks - Google Patents

Method and system for improving transmission of light through photomasks Download PDF

Info

Publication number
US6251545B1
US6251545B1 US09/357,422 US35742299A US6251545B1 US 6251545 B1 US6251545 B1 US 6251545B1 US 35742299 A US35742299 A US 35742299A US 6251545 B1 US6251545 B1 US 6251545B1
Authority
US
United States
Prior art keywords
reflection coating
light
photomask substrate
photomask
film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US09/357,422
Inventor
Harry J. Levinson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GlobalFoundries Inc
Original Assignee
Advanced Micro Devices Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Advanced Micro Devices Inc filed Critical Advanced Micro Devices Inc
Priority to US09/357,422 priority Critical patent/US6251545B1/en
Assigned to ADVANCED MICRO DEVICES reassignment ADVANCED MICRO DEVICES ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LEVINSON, HARRY J.
Priority to US09/742,970 priority patent/US6627355B2/en
Application granted granted Critical
Publication of US6251545B1 publication Critical patent/US6251545B1/en
Assigned to GLOBALFOUNDRIES INC. reassignment GLOBALFOUNDRIES INC. AFFIRMATION OF PATENT ASSIGNMENT Assignors: ADVANCED MICRO DEVICES, INC.
Assigned to WILMINGTON TRUST, NATIONAL ASSOCIATION reassignment WILMINGTON TRUST, NATIONAL ASSOCIATION SECURITY AGREEMENT Assignors: GLOBALFOUNDRIES INC.
Anticipated expiration legal-status Critical
Assigned to GLOBALFOUNDRIES INC. reassignment GLOBALFOUNDRIES INC. RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: WILMINGTON TRUST, NATIONAL ASSOCIATION
Assigned to GLOBALFOUNDRIES U.S. INC. reassignment GLOBALFOUNDRIES U.S. INC. RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: WILMINGTON TRUST, NATIONAL ASSOCIATION
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
    • G03F1/32—Attenuating PSM [att-PSM], e.g. halftone PSM or PSM having semi-transparent phase shift portion; Preparation thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/38—Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/38—Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
    • G03F1/46—Antireflective coatings

Definitions

  • the present invention relates to semiconductor fabrication, and more particularly to lithography in semiconductor fabrication.
  • Lithography is conventionally used in the fabrication of semiconductor devices.
  • a photosensitive film a photoresist
  • the photomask has areas composed of chrome, or some other opaque or partially transmitting material, in a pattern which corresponds to the desired circuitry for the device.
  • the photomasked photoresist is exposed to light from a light source. After exposure, the photomask is removed, leaving a photoresist with the desired pattern.
  • An etch or implantation of the device's substrate may be performed based upon the photoresist pattern.
  • FIG. 1 illustrates a conventional photomask 110 and photoresist 130 as used in lithography.
  • the photomask 1 10 may comprise fused silica.
  • On the bottom side of the photomask 110 are areas 120 .
  • the photomask 110 and photoresist 130 are treated with light from a light source (not shown). The light shines through the photomask 110 where there are no areas 120 . The light is reflected or absorbed where there are areas 120 .
  • Some of the light that passes through the photomask 110 continues through a lens 140 , which projects an image of the mask pattern onto the photoresist 130 , which undergoes a chemical reaction when exposed to light. Portions of the photoresist 150 are exposed to the light while portions of the photoresist 160 are ideally not exposed to the light.
  • the present invention addresses such a need.
  • the present invention provides a method and system for improving the transmission of light through a photomask.
  • the method includes providing a photomask substrate, and applying at least one anti-reflection coating to at least one side of the photomask substrate.
  • the anti-reflection coating reduces the loss of light during lithography due to reflections. This increases the efficiency of the lithography.
  • the method and system has the added advantage of reducing the amount of undesired exposure of a photoresist.
  • FIG. 1 illustrates a conventional photomask and photoresist as used in lithography.
  • FIG. 2 is a flow chart illustrating a method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 3 is a flow chart illustrating a first preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 4 illustrates a photomask blank provided by the first preferred embodiment of the method illustrated in FIG. 3 in accordance with the present invention.
  • FIG. 5 is a flow chart illustrating a second preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 6 illustrates a photomask blank provided by the second preferred embodiment of the method illustrated in FIG. 5 in accordance with the present invention.
  • FIG. 7 is a flow chart illustrating a third preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 8 illustrates a photomask blank provided by the third preferred embodiment of the method illustrated in FIG. 7 in accordance with the present invention.
  • FIG. 9 is a flow chart illustrating a fourth preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 10 illustrates a photomask blank provided by the fourth preferred embodiment of the method illustrated in FIG. 9 in accordance with the present invention.
  • the present invention relates to a system and method for improving the transmission of light through photomasks.
  • the following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
  • Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art.
  • the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
  • FIG. 2 is a flow chart illustrating a method for improving the transmission of light through photomasks in accordance with the present invention.
  • a photomask substrate is provided, via step 210 .
  • the photomask substrate may be comprised of fused silica or some other material.
  • an anti-reflection coating is applied to at least one side of the photomask substrate, via step 220 .
  • An attenuating film may then be applied to one side, forming a photomask blank.
  • the photomask blank is then patterned to form the photomask. Light transmitted through the silica with the anti-reflection coating(s) suffer less loss of light due to reflections. This increases the efficiency of the lithography.
  • the anti-reflection coating can be a single film, usually comprised of materials, such as CaF 2 , MgF 2 , DyF 3 , LaF 3 , Na 3 AlF 6 , YF 3 , and AIM 2 O 3 , although not limited to these materials.
  • the anti-reflection coating may also be a multilayer film comprised of these and other materials, sometimes along with SiO 2 .
  • n is the index of refraction of the material.
  • n 1.5-1.7 for wavelengths between 248 nm and 157 nm, which is the wavelength range of interest for lithography. Accordingly, the reflection from a single surface of the fused silica is 4%-7%. In a lithography application, between 8% and 14% of the light is lost from simple reflections from the two surfaces of the photomask. The application of anti-reflection coating(s) can reduce this reflectance to less than 0.5% per surface. This can enhance lithography productivity significantly.
  • FIG. 3 is a flow chart illustrating a first preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 4 illustrates a photomask blank provided by the first preferred embodiment of the method as illustrated in FIG. 3 .
  • a photomask substrate 410 is provided, via step 310 .
  • the photomask substrate 410 may be comprised of fused silica and has a first (top) side and a second (bottom) side.
  • Anti-reflection coatings 420 and 430 are applied to the first and second sides of the photomask substrate 410 respectively, via step 320 .
  • an attenuating or opaque film 440 may be provided on top of the anti-reflection coating 420 on the first side, via step 330 .
  • the attenuating film 440 is patterned in correspondence to the desired circuitry for the device. In the first preferred embodiment, reflections from both sides of the photomask are decreased.
  • FIG. 5 is a flow chart illustrating a second preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 6 illustrates a photomask blank provided by the second preferred embodiment of the method as illustrated in FIG. 5 .
  • a photomask substrate 610 is provided, via step 510 .
  • An anti-reflection coating 620 is applied to the second side of the photomask substrate 610 , via step 520 .
  • an attenuating film 630 is provided on the first side of the photomask substrate 610 , via step 530 .
  • the integrity of the attenuating film 630 is maintained while reflections from the second side of the photomask substrate 610 are decreased.
  • the efficiency of the lithography is still improved over conventional photomasks with the second preferred embodiment.
  • FIG. 7 is a flow chart illustrating a third preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 8 illustrates a photomask blank provided by the third preferred embodiment of the method as illustrated in FIG. 7 .
  • a photomask substrate 810 is provided, via step 710 .
  • An anti-reflection coating 820 is applied to the first side of the photomask substrate 810 , via step 720 .
  • an attenuating film 830 may be provided on the anti-reflection coating 820 , via step 730 .
  • reflections from the first side of the photomask substrate 810 are decreased. Because there is no anti-reflection coating on the second side, there is no cause for concern about scratching the coating. The efficiency of the lithography is still improved over conventional photomasks with the third preferred embodiment.
  • FIG. 9 is a flow chart illustrating a fourth preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
  • FIG. 10 illustrates a photomask provided by the fourth preferred embodiment of the method as illustrated in FIG. 9 .
  • a photomask substrate 1010 is provided, via step 910 .
  • Anti-reflection coatings 1020 and 1030 are applied to the first and second sides of the photomask substrate 1010 respectively, via step 920 .
  • the anti-reflecting coating 1030 also serves as the alternating phase-shifting film. Then, an attenuating film 1040 may be provided on the alternating phase-shifting film 1030 , via step 930 .
  • n 2 ⁇ k + 1 2 ⁇ k - 1
  • a method and system for improving the transmission of light through photomasks has been disclosed.
  • the method and system applies at least one anti-reflection coating to a side of the photomask.
  • the anti-reflection coating reduces the loss of light during lithography due to reflections. This increases the efficiency of the lithography.
  • the method and system with the exception of the second embodiment, has the added advantage of reducing the amount of undesired exposure of a photoresist due to scatter.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)

Abstract

The present invention provides a method and system for improving the transmission of light through a photomask. The method includes providing a photomask substrate, and applying at least one anti-reflection coating to at least one side of the photomask substrate. The anti-reflection coating reduces the loss of light during lithography due to reflections. This increases the efficiency of the lithography. The method and system has the added advantage of reducing the amount of undesired exposure of a photoresist.

Description

FIELD OF THE INVENTION
The present invention relates to semiconductor fabrication, and more particularly to lithography in semiconductor fabrication.
BACKGROUND OF THE INVENTION
Lithography is conventionally used in the fabrication of semiconductor devices. In optical lithography, a photosensitive film, a photoresist, is patterned by a photomask. The photomask has areas composed of chrome, or some other opaque or partially transmitting material, in a pattern which corresponds to the desired circuitry for the device. The photomasked photoresist is exposed to light from a light source. After exposure, the photomask is removed, leaving a photoresist with the desired pattern. An etch or implantation of the device's substrate may be performed based upon the photoresist pattern.
FIG. 1 illustrates a conventional photomask 110 and photoresist 130 as used in lithography. The photomask 1 10 may comprise fused silica. On the bottom side of the photomask 110 are areas 120. The photomask 110 and photoresist 130 are treated with light from a light source (not shown). The light shines through the photomask 110 where there are no areas 120. The light is reflected or absorbed where there are areas 120. Some of the light that passes through the photomask 110 continues through a lens 140, which projects an image of the mask pattern onto the photoresist 130, which undergoes a chemical reaction when exposed to light. Portions of the photoresist 150 are exposed to the light while portions of the photoresist 160 are ideally not exposed to the light.
However, approximately 4-5% of the light is lost through reflections off each of the two surfaces of the photomask, as illustrated by arrows 170 in FIG. 1. When a large number of devices are fabricated on a substrate, this amount of loss is costly for the manufacturer. In addition, light reflected from the substrate can be transmitted back through the lens and back to the photomask 110. A portion of this light is then reflected by the photomask 110 back to the photoresist 160 on the wafer. Such reflected light is not part of the intended image of the photomask 110, and it can degrade the quality of the light pattern in the photoresist 160.
Accordingly, what is needed is a system and method for improving the transmission of light through photomasks. The method and system should decrease the loss of light due to reflections and decrease undesired exposure of portions of the photoresist. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides a method and system for improving the transmission of light through a photomask. The method includes providing a photomask substrate, and applying at least one anti-reflection coating to at least one side of the photomask substrate. The anti-reflection coating reduces the loss of light during lithography due to reflections. This increases the efficiency of the lithography. The method and system has the added advantage of reducing the amount of undesired exposure of a photoresist.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a conventional photomask and photoresist as used in lithography.
FIG. 2 is a flow chart illustrating a method for improving the transmission of light through photomasks in accordance with the present invention.
FIG. 3 is a flow chart illustrating a first preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
FIG. 4 illustrates a photomask blank provided by the first preferred embodiment of the method illustrated in FIG. 3 in accordance with the present invention.
FIG. 5 is a flow chart illustrating a second preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
FIG. 6 illustrates a photomask blank provided by the second preferred embodiment of the method illustrated in FIG. 5 in accordance with the present invention.
FIG. 7 is a flow chart illustrating a third preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
FIG. 8 illustrates a photomask blank provided by the third preferred embodiment of the method illustrated in FIG. 7 in accordance with the present invention.
FIG. 9 is a flow chart illustrating a fourth preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention.
FIG. 10 illustrates a photomask blank provided by the fourth preferred embodiment of the method illustrated in FIG. 9 in accordance with the present invention.
DETAILED DESCRIPTION
The present invention relates to a system and method for improving the transmission of light through photomasks. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
FIG. 2 is a flow chart illustrating a method for improving the transmission of light through photomasks in accordance with the present invention. First, a photomask substrate is provided, via step 210. The photomask substrate may be comprised of fused silica or some other material. Then, an anti-reflection coating is applied to at least one side of the photomask substrate, via step 220. An attenuating film may then be applied to one side, forming a photomask blank. The photomask blank is then patterned to form the photomask. Light transmitted through the silica with the anti-reflection coating(s) suffer less loss of light due to reflections. This increases the efficiency of the lithography. The amount of undesired exposure of a photoresist (not shown) is decreased as well. The anti-reflection coating can be a single film, usually comprised of materials, such as CaF2, MgF2, DyF3, LaF3, Na3AlF6, YF3, and AIM2O3, although not limited to these materials. The anti-reflection coating may also be a multilayer film comprised of these and other materials, sometimes along with SiO2.
The reflection from light normally incident on a thick planar material is given by: R = ( n - 1 n + 1 ) 2
Figure US06251545-20010626-M00001
where n is the index of refraction of the material. For fused silica, n=1.5-1.7 for wavelengths between 248 nm and 157 nm, which is the wavelength range of interest for lithography. Accordingly, the reflection from a single surface of the fused silica is 4%-7%. In a lithography application, between 8% and 14% of the light is lost from simple reflections from the two surfaces of the photomask. The application of anti-reflection coating(s) can reduce this reflectance to less than 0.5% per surface. This can enhance lithography productivity significantly.
For a single anti-reflecting film, the relationship between the thickness of the film d, the wavelength of the light λ, and the index of refraction n of the material is given by the formula below, where k is a non-negative integer: d = ( 2 k + 1 ) λ 4 n
Figure US06251545-20010626-M00002
FIG. 3 is a flow chart illustrating a first preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention. FIG. 4 illustrates a photomask blank provided by the first preferred embodiment of the method as illustrated in FIG. 3. First, a photomask substrate 410 is provided, via step 310. The photomask substrate 410 may be comprised of fused silica and has a first (top) side and a second (bottom) side. Anti-reflection coatings 420 and 430 are applied to the first and second sides of the photomask substrate 410 respectively, via step 320. Then, an attenuating or opaque film 440 may be provided on top of the anti-reflection coating 420 on the first side, via step 330. The attenuating film 440 is patterned in correspondence to the desired circuitry for the device. In the first preferred embodiment, reflections from both sides of the photomask are decreased.
However, there may be an occasion where the anti-reflection coating is not compatible with the etching of the attenuating film. In this situation, the second preferred embodiment of the present invention, as illustrated in FIGS. 5 and 6, may be used. FIG. 5 is a flow chart illustrating a second preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention. FIG. 6 illustrates a photomask blank provided by the second preferred embodiment of the method as illustrated in FIG. 5. First, a photomask substrate 610 is provided, via step 510. An anti-reflection coating 620 is applied to the second side of the photomask substrate 610, via step 520. Then, an attenuating film 630 is provided on the first side of the photomask substrate 610, via step 530. In the second preferred embodiment, the integrity of the attenuating film 630 is maintained while reflections from the second side of the photomask substrate 610 are decreased. The efficiency of the lithography is still improved over conventional photomasks with the second preferred embodiment.
There may also be an occasion where there is concern about the scratching of the anti- reflection coating which is applied to the second side of the photomask. Typically, the scratching of the second side of the photomask is not a concern due to the hardness of the silica. However, the anti-reflection coating is easily scratched during the handling of the photomask. In this occasion, the third preferred embodiment of the present invention, as illustrated in FIGS. 7 and 8, may be used. FIG. 7 is a flow chart illustrating a third preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention. FIG. 8 illustrates a photomask blank provided by the third preferred embodiment of the method as illustrated in FIG. 7. First, a photomask substrate 810 is provided, via step 710. An anti-reflection coating 820 is applied to the first side of the photomask substrate 810, via step 720. Then, an attenuating film 830 may be provided on the anti-reflection coating 820, via step 730. In the third preferred embodiment, reflections from the first side of the photomask substrate 810 are decreased. Because there is no anti-reflection coating on the second side, there is no cause for concern about scratching the coating. The efficiency of the lithography is still improved over conventional photomasks with the third preferred embodiment.
The method and system in accordance with the present invention may also be used for alternating phase-shifting photomasks, as illustrated in FIGS. 9 and 10. Alternating phase-shifting photomasks are well known in the art and will not be discussed in detail here. FIG. 9 is a flow chart illustrating a fourth preferred embodiment of the method for improving the transmission of light through photomasks in accordance with the present invention. FIG. 10 illustrates a photomask provided by the fourth preferred embodiment of the method as illustrated in FIG. 9. First, a photomask substrate 1010 is provided, via step 910. Anti-reflection coatings 1020 and 1030 are applied to the first and second sides of the photomask substrate 1010 respectively, via step 920. The anti-reflecting coating 1030 also serves as the alternating phase-shifting film. Then, an attenuating film 1040 may be provided on the alternating phase-shifting film 1030, via step 930. In the fourth preferred embodiment, the alternating phase-shifting film 1030 provides anti-reflection capabilities and 1800 phase-shifting to the light. This is accomplished by satisfying the following equations: t 1 = ( 2 m + 1 ) λ 4 n t 2 - t 1 = ( 2 k + 1 ) λ 4 n     = λ 2 ( n - 1 )
Figure US06251545-20010626-M00003
where m and k are non-negative integers, and n is the index of refraction of the alternating phase-shifting film 1030. t1 and t2 are the thickness of the alternating phase-shifting film 1030 beside the attenuating film 1040 as illustrated in FIG. 10. The area with t2 thickness is a zero phase shifting area while the area with t1 thickness is a 180° phase shifting area. From the last two equations, the following result is obtained: n = 2 k + 1 2 k - 1
Figure US06251545-20010626-M00004
When k=3, n=1.4. This can be approximately satisfied with light at 157 nm wavelength for MgF2 (n=1.47) and LiF (n=1.49).
A method and system for improving the transmission of light through photomasks has been disclosed. The method and system applies at least one anti-reflection coating to a side of the photomask. The anti-reflection coating reduces the loss of light during lithography due to reflections. This increases the efficiency of the lithography. The method and system, with the exception of the second embodiment, has the added advantage of reducing the amount of undesired exposure of a photoresist due to scatter.
Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one or ordinary skill in the art without departing from the spirit and scope of the appended claims.

Claims (10)

What is claimed is:
1. A method for transmission of light through a photomask, comprising the steps of:
(a) providing a photomask substrate; and
(b) providing an attenuating film on a first side of the photomask substrate, and applying at least one anti-reflection coating to the first side of the photomask substrate, wherein a reflection of the light from the photomask substrate is reduced and
(c) providing a pattern on the attenuating film and the at least one anti-reflection coating, wherein no attenuating film or anti-reflection coating is applied on the pattern.
2. The method of claim 1, wherein the providing step (a) comprises:
(a1) providing a fused silica.
3. The method of claim 1, wherein the applying step (b) comprises:
(b1) applying the at least one anti-reflection coating on the first side of the photomask substrate; and
(b2) providing the attenuating film on the at least one anti-reflection coating.
4. (Twice Amended) The method of claim 1, wherein the applying step (b) comprises:
(b1) applying a first anti-reflection coating on the first side of the photomask substrate, the first anti-reflection coating providing alternating phase-shifting;
(b2) applying a second anti-reflection coating on a second side of the photomask substrate; and
(b3) providing the attenuating film on the first anti-reflection coating.
5. A system, comprising:
a photomask substrate;
an attenuating film on a first side of the photomask substrate; and
at least one anti-reflection coating on the first side of the photomask substrate,
wherein a reflection of light from the photomask substrate is reduced; and
a pattern on the attenuating film and the at least one anti-reflection coating, wherein no attenuating film or anti-reflection coating is applied on the pattern.
6. The system of claim 5 wherein the at least one anti-reflection coating comprises:
a first anti-reflection coating on a first side of the photomask substrate; and
a second anti-reflection coating on a second side of the photomask substrate.
7. A method for transmission of light through a photomask, comprising the steps of:
(a) providing a photomask substrate;
(b) applying a first anti-reflection coating to a first side of the photomask substrate;
(c) applying a second anti-reflection coating to a second side of the photomask substrate, wherein a reflection of the light from the photomask substrate is reduced;
(d) providing an attenuating film on the first anti-reflection coating; and
(e) providing a pattern on the first anti-reflection coating and the attenuating film wherein no attenuating film or anti-reflection coating is applied to the pattern.
8. A method for transmission of light through a photomask, comprising the steps of:
(a) providing a photomask substrate;
(b) applying a first anti-reflection coating on a first side of the photomask substrate, the first anti-reflection coating providing alternating phase-shifting;
(c) applying a second anti-reflection coating on a second side of the photomask substrate;
(d) providing an attenuating film on the alternating phase-shifting film, wherein a reflection of the light from the photomask substrate is reduced; and
(e) providing a pattern on the alternating phase-shifting film and the attenuating film, wherein no anti-reflection coating or attenuating film is applied on the pattern.
9. A system, comprising:
a photomask substrate;
a first anti-reflection coating on a first side of the photomask substrate; and
a second anti-reflection coating on a second side of the photomask substrate, wherein a reflection of a light from the photomask substrate is reduced;
an attenuating film on the first anti-reflection coating and
a pattern on the first anti-reflection coating and the attenuating film, wherein no anti-reflection coating or attenuating film is applied on the pattern.
10. A system, comprising:
a photomask substrate;
a first anti-reflection coating on a first side of the photomask substrate, the first anti-reflection coating providing alternating phase-shifting;
a second anti-reflection coating on a second side of the photomask substrate;
an attenuating film on the first anti-reflection coating, wherein a reflection of a light from the photomask substrate is reduced; and
a pattern on the alternating phase shifting film and the attenuating film, wherein no anti-reflection coating or attenuating film is applied on the pattern.
US09/357,422 1999-07-20 1999-07-20 Method and system for improving transmission of light through photomasks Expired - Lifetime US6251545B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US09/357,422 US6251545B1 (en) 1999-07-20 1999-07-20 Method and system for improving transmission of light through photomasks
US09/742,970 US6627355B2 (en) 1999-07-20 2000-12-20 Method of and system for improving stability of photomasks

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US09/357,422 US6251545B1 (en) 1999-07-20 1999-07-20 Method and system for improving transmission of light through photomasks

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US09/742,970 Continuation-In-Part US6627355B2 (en) 1999-07-20 2000-12-20 Method of and system for improving stability of photomasks

Publications (1)

Publication Number Publication Date
US6251545B1 true US6251545B1 (en) 2001-06-26

Family

ID=23405526

Family Applications (1)

Application Number Title Priority Date Filing Date
US09/357,422 Expired - Lifetime US6251545B1 (en) 1999-07-20 1999-07-20 Method and system for improving transmission of light through photomasks

Country Status (1)

Country Link
US (1) US6251545B1 (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003038522A1 (en) * 2001-10-26 2003-05-08 Corning Incorporated Anti-reflective coating on a photomask
US20040063001A1 (en) * 2002-09-30 2004-04-01 Wu Wei E. Method of making an integrated circuit using a photomask having a dual antireflective coating
US6797439B1 (en) * 2001-03-30 2004-09-28 Schott Lithotec Ag Photomask with back-side anti-reflective layer and method of manufacture
WO2007039161A1 (en) * 2005-09-27 2007-04-12 Schott Ag Mask blanc and photomasks having antireflective properties
US20100129736A1 (en) * 2008-06-17 2010-05-27 Kasprowicz Bryan S Photomask Having A Reduced Field Size And Method Of Using The Same
WO2011011332A1 (en) * 2009-07-21 2011-01-27 Ultra Communications, Inc. Patterned backside optical coating on transparent substrate
US20110086511A1 (en) * 2009-06-17 2011-04-14 Kasprowicz Bryan S Photomask having a reduced field size and method of using the same
US8871102B2 (en) 2011-05-25 2014-10-28 Western Digital (Fremont), Llc Method and system for fabricating a narrow line structure in a magnetic recording head
US9034564B1 (en) 2013-07-26 2015-05-19 Western Digital (Fremont), Llc Reader fabrication method employing developable bottom anti-reflective coating
US9431040B1 (en) 2009-09-16 2016-08-30 Western Digital (Fremont), Llc Magnetic recording transducer

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5279911A (en) * 1990-07-23 1994-01-18 Mitsubishi Denki Kabushiki Kaisha Photomask
US5422206A (en) * 1991-05-24 1995-06-06 Mitsubishi Denki Kabushiki Kaisha Photomask and method of manufacturing the same
US5780161A (en) * 1996-11-06 1998-07-14 Taiwan Semiconductor Manufacturing Company Ltd. Non-absorbing anti-reflective coated (ARC) reticle using thin dielectric films and method of forming the reticle
US5879866A (en) * 1994-12-19 1999-03-09 International Business Machines Corporation Image recording process with improved image tolerances using embedded AR coatings

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5279911A (en) * 1990-07-23 1994-01-18 Mitsubishi Denki Kabushiki Kaisha Photomask
US5422206A (en) * 1991-05-24 1995-06-06 Mitsubishi Denki Kabushiki Kaisha Photomask and method of manufacturing the same
US5879866A (en) * 1994-12-19 1999-03-09 International Business Machines Corporation Image recording process with improved image tolerances using embedded AR coatings
US5780161A (en) * 1996-11-06 1998-07-14 Taiwan Semiconductor Manufacturing Company Ltd. Non-absorbing anti-reflective coated (ARC) reticle using thin dielectric films and method of forming the reticle

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Characteristics of Deep UV Optics at 193nm & 157 nm," Glen P. Callahan and Bruce K. Flint 1998.
GLEN P. CALLAHAN; BRUCE K. FLINT: "Characteristics of Deep UV Optics at 193nm & 157 nm", PROCEEDINGS OF SPIE, SPIE, vol. 3578, 7 April 1999 (1999-04-07), pages 45 - 53, XP009534208, ISSN: 0277-786X, DOI: 10.1117/12.344438

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6797439B1 (en) * 2001-03-30 2004-09-28 Schott Lithotec Ag Photomask with back-side anti-reflective layer and method of manufacture
WO2003038522A1 (en) * 2001-10-26 2003-05-08 Corning Incorporated Anti-reflective coating on a photomask
US20040063001A1 (en) * 2002-09-30 2004-04-01 Wu Wei E. Method of making an integrated circuit using a photomask having a dual antireflective coating
WO2007039161A1 (en) * 2005-09-27 2007-04-12 Schott Ag Mask blanc and photomasks having antireflective properties
US20100129736A1 (en) * 2008-06-17 2010-05-27 Kasprowicz Bryan S Photomask Having A Reduced Field Size And Method Of Using The Same
US9005848B2 (en) 2008-06-17 2015-04-14 Photronics, Inc. Photomask having a reduced field size and method of using the same
US20110086511A1 (en) * 2009-06-17 2011-04-14 Kasprowicz Bryan S Photomask having a reduced field size and method of using the same
US9005849B2 (en) 2009-06-17 2015-04-14 Photronics, Inc. Photomask having a reduced field size and method of using the same
WO2011011332A1 (en) * 2009-07-21 2011-01-27 Ultra Communications, Inc. Patterned backside optical coating on transparent substrate
US9431040B1 (en) 2009-09-16 2016-08-30 Western Digital (Fremont), Llc Magnetic recording transducer
US8871102B2 (en) 2011-05-25 2014-10-28 Western Digital (Fremont), Llc Method and system for fabricating a narrow line structure in a magnetic recording head
US9034564B1 (en) 2013-07-26 2015-05-19 Western Digital (Fremont), Llc Reader fabrication method employing developable bottom anti-reflective coating

Similar Documents

Publication Publication Date Title
US6818361B2 (en) Photomasking
US5609977A (en) Reflection phase shifting mask and method of forming a pattern using the same
JP2007133102A (en) Optical element having reflection preventing film, and exposure apparatus having the same
JPH0555120A (en) Reflection-type mask and manufacture and correction thereof
US6627355B2 (en) Method of and system for improving stability of photomasks
US6576375B1 (en) Photomask
US6251545B1 (en) Method and system for improving transmission of light through photomasks
US7029804B2 (en) Non absorbing reticle and method of making same
JPH10186632A (en) Blank for halftone type phase shift mask and halftone type phase shift mask
US6797439B1 (en) Photomask with back-side anti-reflective layer and method of manufacture
US6593037B1 (en) EUV mask or reticle having reduced reflections
JP5089362B2 (en) Photomask and exposure method
JPH04162039A (en) Photomask
JPH1115132A (en) Halftone type phase shift mask and blank for halftone type phase shift mask
US20070134563A1 (en) Photomask and method of manufacturing semiconductor device
US6759171B1 (en) Alternating aperture phase shifting photomask with improved intensity balancing
JP3526207B2 (en) Antireflection film and optical system provided with the same
US20040165271A1 (en) Enhancing light coupling efficiency for ultra high numerical aperture lithography through first order transmission optimization
JP3178516B2 (en) Phase shift mask
JPS63204259A (en) Mask
JP3110245B2 (en) Reflective exposure mask and pattern forming method
JPH1026820A (en) Halftone phase shift mask blank, and halftone phase shift mask
JP2002189101A (en) Antireflection film, optical element and exposure device
US5294506A (en) Photomask
JP3943740B2 (en) Antireflection film and optical system provided with the same

Legal Events

Date Code Title Description
AS Assignment

Owner name: ADVANCED MICRO DEVICES, CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEVINSON, HARRY J.;REEL/FRAME:010120/0598

Effective date: 19990715

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

AS Assignment

Owner name: GLOBALFOUNDRIES INC., CAYMAN ISLANDS

Free format text: AFFIRMATION OF PATENT ASSIGNMENT;ASSIGNOR:ADVANCED MICRO DEVICES, INC.;REEL/FRAME:023119/0083

Effective date: 20090630

FPAY Fee payment

Year of fee payment: 12

AS Assignment

Owner name: WILMINGTON TRUST, NATIONAL ASSOCIATION, DELAWARE

Free format text: SECURITY AGREEMENT;ASSIGNOR:GLOBALFOUNDRIES INC.;REEL/FRAME:049490/0001

Effective date: 20181127

AS Assignment

Owner name: GLOBALFOUNDRIES INC., CAYMAN ISLANDS

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:WILMINGTON TRUST, NATIONAL ASSOCIATION;REEL/FRAME:054636/0001

Effective date: 20201117

AS Assignment

Owner name: GLOBALFOUNDRIES U.S. INC., NEW YORK

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:WILMINGTON TRUST, NATIONAL ASSOCIATION;REEL/FRAME:056987/0001

Effective date: 20201117